Thousands of low-paid female workers at Glasgow City Council are set to share in a payout believed to be worth up to £50 million after a senior judge ruled in their favour in a long-running pay dispute.

The Court of Session ruled that women employees at Scotland’s largest council had been excluded from sizeable bonuses for many years and had been discriminated against for three years when they were trying to sort out equal pay claims.

Around 6,000 workers believed they had been discriminated against and launched legal action through trade unions Unison and the GMB.

Union sources said the payouts from this case alone will cost the city council tens of millions of pounds, with one citing a figure “of at least £50million” in back-dated claims for the discriminated workers.

Council bosses are not planning to appeal the legal ruling, marking the end of the long-running battle.

Unions had argued that while the claimants had been unfairly discriminated against before the new system was introduced a decade ago, the city council’s decision to continue the unequal pay was also discriminatory as it excluded women claimants from pay protection.

Union leaders hailed the decision as a huge victory. GMB Scotland secretary Gary Smith said:

“After years of legal wrangling by Glasgow City Council, this morning’s judgment paves the way for thousands of low-paid women to claim justice.

“The vast majority of them are our carers, caterers and cleaners, employed on the bottom rungs of the local government pay spine yet making some of the biggest contributions to the running of our local services.”

Mike Kirby, Unison’s Scottish Secretary, said:

“The pay protection win is great news. The way Glasgow rates and pays workers has been the source of conflict and division for ten years. These women have already waited long enough to receive the pay they have worked hard for and deserve. It’s time for Glasgow City Council to do the right thing and pay up on equal pay.”

The Court of Session has also been asked to consider whether the current council pay system is a valid pay scheme.

Unison had challenged the council’s method of measuring the value of jobs, in particular the use of different scales, one for core pay and others for non-core pay.

The union had argued the system made it impossible for employees to know if they were being paid equal.

Susan Aitken, Leader of Glasgow City Council said:

“This is a complex legal ruling. However it is now clear that the award of pay protection was done in a way which discriminated against some of our female workers at that time

“The right thing to do now is for the council to have open discussions with those workers and their representatives about how we give effect to this ruling. I hope there will be goodwill on both sides during those discussions.”